C0NN9510C Carburetor for Ford 800 / 900 / 4000 Series — 172ci Gas Engine

Your Ford tractor won't start, idles rough, surges under load, or dumps fuel out of the throat. The original carburetor on your 172 cubic inch gas engine is worn out — the throttle shaft is sloppy, the float needle is leaking, and the accelerator pump diaphragm has cracked. You can spend $150+ on a rebuild kit and hope the casting isn't warped, or you can bolt on a brand new carburetor and be back in the field in 30 minutes.

The dealers and big-box retailers want $380 to $600+ for this carburetor. We sell the same direct replacement for $349 — saving you over $200. This is a complete, brand new carburetor that bolts directly onto the intake manifold of your Ford 172ci gas engine. Replaces Ford part numbers C0NN9510C and C0NN9510G.

⚠️ Critical: Verify Your Mounting Bolt Spacing Before Ordering

This is the #1 mistake people make when ordering a Ford tractor carburetor. There are TWO different carburetors for Ford N-Series and Hundred-Series tractors, and they are NOT interchangeable:

2-11/16" Mounting Bolt Spacing (This Listing): For the larger 172 cubic inch gas engine used in the Ford 800, 900, and 4000 Series. Fuel inlet is 7/16" thread. Throat diameter is 1-5/16". This is the correct carburetor for your tractor.
2-3/8" Mounting Bolt Spacing (NOT This Listing): For the smaller 134 cubic inch gas engine used in the Ford 600, 700, and 2000 Series. This is a physically smaller carburetor with a 3/8" fuel inlet. It WILL NOT FIT the 172ci engine.

How to check: Measure the distance between the center of the two mounting bolt holes on your intake manifold. If the distance is 2-11/16" (approximately 2.69 inches), this is the correct carburetor. If the distance is 2-3/8" (approximately 2.375 inches), you need the smaller Ford 600/700 carburetor — contact us.

The Problem

Ford 172ci gas engines use a downdraft carburetor that was state-of-the-art in the 1950s and 1960s. These carburetors have been in service for 60–70+ years on tractors that are still working every day on farms, ranches, and small properties across America. Time takes its toll:

Throttle shaft bushings wear out, creating an air leak that makes the engine run lean and surge
The float needle valve wears and allows fuel to flood the carburetor bowl
Accelerator pump diaphragms crack and the engine stumbles on acceleration
Internal passages corrode and plug with varnish from old gas
The choke mechanism sticks, making cold starts impossible
The main metering jet wears out of spec, running the engine too rich or too lean

A rebuild kit can help if the casting is in good shape, but if the throttle shaft bores are egg-shaped or the casting is warped, no rebuild kit will fix it. A complete new carburetor is faster, more reliable, and often cheaper than a professional rebuild.

The Solution

This is a complete, brand new replacement carburetor built to the same specifications as the original Ford C0NN9510C / C0NN9510G. Same 2-11/16" mounting bolt spacing, same 7/16" fuel inlet thread, same 1-5/16" throat diameter. It bolts directly onto the intake manifold of your Ford 172ci gas engine with no modifications, no adapters, and no machining. Remove the old carburetor, transfer the fuel line and throttle linkage, bolt on the new one, and you're running.

Specifications

Ford OEM Part Number: C0NN9510C (also replaces C0NN9510G, 312955, 310015)
Type: Downdraft Carburetor — Complete Assembly
Mounting Bolt Spacing: 2-11/16" (2.6875") — VERIFY BEFORE ORDERING
Fuel Inlet: 7/16" Thread
Throat Diameter: 1-5/16"
Engine: Ford 172 Cubic Inch Gas (Red Tiger)
Choke: Manual
Includes: Complete carburetor with gaskets
Condition: Brand New

Compatible Equipment

The C0NN9510C carburetor fits the following Ford tractor models equipped with the 172 cubic inch gas engine:

Ford 800 Series: 800, 801, 811, 820, 821, 840, 841, 850, 851, 860, 861
Ford 900 Series: 900, 901, 940, 941, 950, 951, 960, 961, 971, 981
Ford 1800 Series: 1801, 1811, 1821, 1841, 1871, 1881
Ford 4000 Series (4-Cylinder): 4000, 4030, 4031, 4040, 4120, 4121, 4130, 4131, 4140
Ford Industrial: 871, 881

⚠️ The Ford 4000 was produced in different generations with different engines. Pre-1965 models used the 172ci gas engine. Later 4000 Series models used a 3-cylinder diesel or a different gas engine. Verify your engine displacement before ordering. If you see "172 CID" or "Red Tiger" on your engine data plate, this is the correct carburetor.

Installation Notes

Disconnect the battery (if equipped) and allow the engine to cool completely
Shut off the fuel supply valve at the tank
Disconnect the fuel line at the carburetor fuel inlet
Disconnect the throttle linkage and choke cable/rod
Remove the two mounting bolts/nuts securing the carburetor to the intake manifold
Lift the old carburetor off the intake manifold — note the gasket condition
Clean the intake manifold mounting surface thoroughly — remove all old gasket material
Place the new gasket (included) on the intake manifold
Set the new carburetor onto the manifold and hand-start the mounting bolts
Tighten the mounting bolts evenly — do NOT overtighten (the manifold can crack)
Reconnect the fuel line to the 7/16" fuel inlet — use a new copper washer if available
Reconnect the throttle linkage and choke mechanism
Open the fuel valve and check for leaks at the fuel inlet connection
Set the mixture screw to 1-1/2 turns out from fully seated as a starting point
Start the engine, allow it to warm up, and fine-tune the idle mixture and idle speed
Verify throttle response across the full range — from idle to full governed RPM

Symptoms of a Failing Carburetor

Engine won't start or is very hard to start
Engine idles rough, surges, or stalls at idle
Engine stumbles or bogs on acceleration
Black smoke from the exhaust (running too rich)
Engine backfires through the carburetor or exhaust
Fuel leaking from the carburetor throat or bowl
Engine runs but has no power under load
Choke mechanism stuck or inoperative
Throttle has excessive play or doesn't respond properly
Engine runs fine at idle but dies under load (plugged passages)
Strong fuel smell around the tractor (leaking float valve)

Frequently Asked Questions

How do I know if I need the 2-11/16" or 2-3/8" carburetor?
Measure the distance between the center of the two mounting bolt holes on your intake manifold. The 172ci engine (Ford 800/900/4000) uses the 2-11/16" spacing. The 134ci engine (Ford 600/700/2000) uses the 2-3/8" spacing. You can also check the fuel inlet fitting — the 172ci carburetor uses a larger 7/16" thread, while the 134ci uses 3/8". If you're still unsure, contact us with your tractor model and engine serial number.

What is the difference between C0NN9510C and C0NN9510G?
These are the same carburetor. Ford revised the part number over the years, but the physical carburetor is identical. C0NN9510G supersedes C0NN9510C. This carburetor replaces both part numbers.

Does this carburetor need any adjustment out of the box?
Set the idle mixture screw to approximately 1-1/2 turns out from fully seated as a starting point. Start the engine, let it reach operating temperature, then fine-tune the idle mixture for smoothest idle. Adjust the idle speed screw for the correct idle RPM per your operator's manual. The float level is pre-set at the factory.

Will this work on a Ford 600 or 700?
No. The Ford 600 and 700 Series use the smaller 134ci gas engine with a carburetor that has 2-3/8" mounting bolt spacing and a 3/8" fuel inlet. This carburetor has 2-11/16" spacing and a 7/16" inlet — it will not bolt onto the 134ci intake manifold. Contact us for the correct 600/700 carburetor.

My tractor has been sitting for years and the carburetor is full of varnish. Should I rebuild or replace?
If the tractor has been sitting for many years, a complete replacement is almost always the better choice. Old fuel turns to varnish that clogs internal passages, the throttle shaft bushings wear egg-shaped (causing air leaks), and the aluminum casting can corrode. A rebuild kit cannot fix a worn casting. A new carburetor gives you a fresh start with correct tolerances and new internal components. It's also faster — 30 minutes to swap vs several hours to rebuild.

Ford

Equipment Models

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Ford Parts (1)

C0NN9510C Ford Tractor Carburetor - 172ci Gas Engine - Ford 800 900 4000 Series - 2-11/16" Mounting - Replaces C0NN9510G